The Hittite documents show many instances of an interchange of the vowels e and a . Since the variation is not uniform, and neither vowel of the pair is restricted to any phonetic surroundings or morphological categories, we must apparently assume several causes, and sound method requires the separate treatment of groups of words which show parallel phenomena. In this paper I propose to discuss the variation in monosyllabic verbal roots which end in a consonant.
E. H. Sturtevant (Thu,) studied this question.
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